Integumentary system

Stratum lucidum

"clear" layer of the epidermis, in thick skin between the stratum granulosum and the stratum corneum

The two main layers that compose the skin are the dermis and

epidermis

thin skin

covers most of the body surface

Stratum granulosum

"granular layer" layer in which the process of keratinization begins; two to four layers; high level of lysosomal enzymes

Stratum spinosum

"spiny layer"; layer of epidermis that is rich in RNA to aid in protein synthesis required for keratin production; 8-10 layers; the desmosomes pull points of the plasma membrane of the adjoining cells toward one another

thickness of eyelids

0.5mm

strata

5 layers of skin

thickness of back skin

5mm

epidermal proliferating unit

Cells migrating to the surface proceed upward in vertical columns from discrete groups of 8-10 of these basal cells undergoing mitosis; each group of active basal cells, together with its vertical columns of migrating keratinocytes, is called (EPU)

Which of the following is not a function of the skin?

Contraction

What are the two types of sweat glands? How do they differ?

Eccrine: the most numerous and widespread of the sweat glands in the body. They are small and function throughout life to produce perspiration rich in salts, ammonia, uric acid, urea, and other wastes. Apocrine: glands located deep in the subcutaneous layer. They are much larger than eccrine glands and are connected with hair follicles. Apocrine glands enlarge and begin to function at puberty, producing a more viscous and colored secretion.

Identify the two main or primary layers of skin. What tissue type dominates each layer?

Epidermis and dermis are the primary skin layers. Epithelium dominates the epidermal layer and connective tissue dominates the dermis.

Name three of the four physical processes by which heat is lost from the body.

Evaporation, radiation, conduction, and convection are the processes by which heat is lost from the body.

List the appendages of the skin.

Hair, nails, and skin glands are the appendages of the skin.

Identify the two main cell types found in the epidermis.

Keratinocytes and melanocytes are the two main cell types in the epidermis.

What is the one mean of heat production in the body? In what type of organs does most heat production occur?

Metabolism of foods is the source of body heat. Muscles and glands produce more heat than any other tissues.

The terms thin and thick skin refer to which primary layer of skin? How do think and thick skin differ?

Most of the body surface is covered by thin skin. Skin covering the palms of the hands, soles of the feet, and other body areas subject to friction is classified as thick skin. In thin skin, the number of cell layers in each epidermal stratum is less than that in thick skin. Raised parallel ridges are not present in the dermis of thin skin.

Dermis has two layers..

Papillary layer and Reticular layer

List seven functions of the skin.

Protection, sensation, growth, synthesis of important chemicals and hormones, excretion, temperature regulation, and immunity are the functions of the skin.

List two functions of sebum.

Sebum keeps the hair supple and the skin soft and pliant.

List the five layers, or strata, of the epidermis.

Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale are the five layers of the epidermis.

What substances make up the skin's surface film?

Surface film of the skin is produced by the mixing of residue and secretions from sweat and sebaceous glands with epithelial cells.

Dermoepidermal junction (DEJ)

The area where the cells of the epidermis meet the connective tissue cells of the dermis

Which layer of the dermis forms the bumps that produce ridges on the palms and soles?

The dermal papillae forms the bumps that produce ridges.

What is the name of the gluelike layer separating the dermis from the epidermis?

The dermal-epidermal junction separates the dermis and epidermis.

Which layer is vascular: the epidermis or dermis?

The dermis layer is vascular.

What is the main function of the hypodermis?

The hypodermis forms a connection between the skin and the underlying structures of the body.

How does surface film contribute to the protective function of the skin?

The surface film is produced by the mixing of residue and secretions from sweat and sebaceous glands, with the epithelial cells constantly being cast off from the epidermis.

Identify the pigment that determines hair color.

Varying amounts of melanin determine hair color.

dermal papillae

any of the many small bumps in the surface of the papillary layer of the dermis and which form the ridges and grooves of fingerprints

antigen-presenting cell (APC)

any variety of immune cells that present protein fragments (antigens) on their surface and thus allow recognition and reaction by other immune system cells; include macrophages and dendritic cells;

Each hair follicle has a small bundle of involuntary muscles attached to it called the:

arrector pili muscles

Stratum basale

base layer; deepest layer of the epidermis; cells in this layer are able to reproduce themselves; only layer that goes through mitosis

hypodermis

beneath the dermis; rich in fat; loose fibrous connective tissue

Melanocytes

cell type in the stratum basale of the skin that produces melanin pigment granules, releasing them to other nearby skin cells

The mixed secretions of sebaceous and ceruminous glands form a brown waxy substance called the:

cerumen

The shedding of epithelial elements from the skin surface is called:

desquamation

germ layer where epidermis comes from

ectodermal germ layer

Keratinocytes

epidermal cell responsible for synthesizing keratin

two primary layers that compose the skin

epidermis and dermis

thick skin

hairless skin covering the palms of the hands (and fingertips), soles of the feet, and other body areas subject to friction

calluses

in skin, abnormally thick stratum corneum found at points of friction

friction ridges (epidermal ridges)

in thick skin the underlying dermal papillae are raising in curving parallel epidermal ridges; to form fingerprints or footprints that are visible on the overlaying epidermis; increase friction to help is manipulate small objects with the hands and provide slip resistance to the sole of the feet; also act as sensory organs, amplifying vibrations as we lightly swipe across a textured surface.

The epidermis is composed of several types of epithelial cells. One type, called keratinocytes, become filled with a tough, fibrous protein called:

keratin

Around the sixth month of pregnancy, the developing fetus is almost entirely covered by a fine soft hair coat called the:

lanugo

skin thickness varied from..

less than 0.05 cm (1/50 inch) to slightly more than 0.3 cm (1/8 inch)

Papillary layer

loose fibrous tissue with collagenous and elastic fibers; forms nipplelike bumps; includes tactile corpuscles (touch receptors) and other sensory receptors

The basic determinant of skin color is

melanin

germ layer where dermis comes from

mesoderm

dendritic cells (DCs)

phagocytic cells in the skin; also called Langerhans cells; branched cells that play a role in immunity; type of antigen-presenting cell (APC); originate in the bone marrow but migrate to the deep cells lattes of the epidermis early in life.

keratinization

process by which cells of the stratum corneum become fitted with keratin and move to surface

The dermis is composed of two layers, a thin papillary layer and a thick _____ layer.

reticular

average-sized adults skin surface area

roughly 1.6-1.9 meters squared (17 to 20 square feet)

keratohyalin

staining granules located within the stratum lucid; required for surface keratin formation

Tactile epithelial cells (Merkel cells)

stiff epithelial cell of the epidermis of the skin that passes compression of the skin for light or discriminative touch

Epidermis

superficial, thinner layer; epithelial layer derived from the ectodermal germ layer of the embryo

The skin glands include three kinds of microscopic glands. They are the __________ glands.

sweat, sebaceous, and ceruminous

Stratum germinativum

synonym for stratum basal of the skin epidermis; sometimes used to denote stratum basale and stratum spinosum together

integumentary system

term used to denote the skin and its appendages

Dermis

the deep, thicker layer; derived from the mesoderm germ layer; is relatively dense and vascular connective tissue later that may average more than 4mm in thickness in some body areas.

by the 17th week of gestation

the epidermis of the developing baby has all the essential characteristics of the adult

cutaneous membrane

the skin is a thin, relatively flat organ classified as a membrane

hyperkeratosis

thickening of the horny layer of the skin

stratum corneum

tough outer layer of the epidermis; cells are filled with keratin